Properties of Triangles

I missed a week of school and I have a quiz tom on properties of triangles can someone give me a little review on it.

For example
Scalane traingle

bottom right side is (x-15)deg
on the left corner there is an suplmentary extension of 150 so you sutract is by 180 and that gives you 30.
But it says solve for x which is the top of the triangle and im not sure how to do it....

Scalane triangle
Bottom right side is (x-15)deg
On the left corner there is an supplementary extension of 150°
so you subtract from180 and that gives you 30°.
It says: solve for x which is the top of the triangle